The present invention relates to a systems and methods for inhibiting backend access to integrated circuits (ICs) by integrating photon and electron sensing latch-up circuits (LCs) into integrated circuits to cause a catastrophic latch-up condition when the integrated circuits are powered.
In modern computing, ICs play an ever-increasing role in creating advanced hardware components. Two common problems encountered in the computing industry are unauthorized modifications to ICs and piracy of proprietary designs and information. Both of these problems can occur when competitors and other individuals have backend access to an IC. For piracy, individuals can inspect and probe an IC to determine the functionality of individual circuits and components. With backend access, an individual can copy proprietary information with ease. For unauthorized modifications, individuals with backend access can make changes to an integrated circuit with a variety of techniques (e.g., a focused ion beam (FIB)). Modifications can include attempts to change the functionality of an IC beyond the manufacturer's intended purpose (e.g., repurpose an IC to function in a competing product) or attempts to subvert the proper functionality of an IC while hiding evidence that the modifications occurred (e.g. diminish the effectiveness of a system).
To solve these problems, embodiments of this invention disclose incorporating LCs into an integrated circuit so that unauthorized backend access triggers a binary trip sensor (e.g., a floating gate bit cell) to activate LCs when particular conditions are met. An excess number of electrons placed on a floating gate bit cell can create a negative channel bias, which places a floating gate bit cell in an “off” state such that a LC will not activate when a connected IC is powered. Triggering a floating gate bit cell causes a connected LC to close. Closing the LC results in a positive feedback loop which will short-circuit the integrated circuit. A short-circuit will restrict unauthorized individuals from being able to effectively modify or probe the integrated circuit by rendering the circuit inoperable.
According to an illustrative embodiment of the present disclosure, at least one LC is connected to an IC. The LC can include a charged floating gate. A floating gate can lose its charge when exposed to photons, electrons, or ions. Ions (e.g. gallium ions, helium ions) can be used in a focused ion beam (FIB) to modify an IC. The ions in a FIB will trigger a floating gate bit cell, so attempts to modify an IC with a FIB can activate a LC and cause latch-up events to occur.
According to a further illustrative embodiment of the present disclosure, at least one LC is connected to an IC. The LC can include a photodiode connected to a charged floating gate. When the photodiode receives light, the photodiode causes the floating gate to lose its charge and close the circuit, which closes the LC and causes short-circuits if the IC is powered.
Additional features and advantages of the present invention will become apparent to those skilled in the art upon consideration of the following detailed description of the illustrative embodiment exemplifying the best mode of carrying out the invention as presently perceived.